This invention relates to a fuel injection system and more particularly to an improved injection system that employs a pair of fuel injectors each of which injects fuel at a different pressure.
The use of direct cylinder injection has several advantages. These advantages may be employed with both two and four cycle engines. However, when direct cylinder injection is used in a two cycle, then only pure air is inducted into the crank case. Because of this and the fact that a two cycle engine fires on every crankshaft revolution rather than every other crankshaft revolution, direct injection into the combustion chamber of a two cycle engine might give rise to problems in connection with inadequate piston cooling and high combustion chamber temperature. Therefore, it has been proposed to inject at least a small amount of fuel into the intake system under at least high load conditions so as to achieve piston cooling.
Where two fuel injectors are employed that inject fuel into the different areas of the engine there are certain problems which arise. For example, the injection nozzle that sprays into the combustion chamber must be supplied with fuel at a relatively high pressure. However, high pressure fuel should not be injected into the induction passage because this can give rise to excess fuel deposit on the induction passages. Also, the use of high pressure fuel makes it difficult to control the amount of fuel being injected into such a low pressure area and control problems can arise. If, however, the injection pressure is reduced, the combustion chamber fuel injector may not supply adequate fuel for high performance and control can become a problem. If separate pressure pumps and pressure regulators are applied for each of the injection nozzles, the system becomes expensive and complicated.
It is, therefore, a principal object of this invention to provide an improved fuel injection system for an engine.
It is a further object of this invention to provide a fuel injection system for an engine wherein two fuel injectors are employed and each is supplied with fuel from the same source and same fuel pump and at different pressures.
It is a further object of this invention to provide an improved and simplified delivery and regulating system for multiple injection nozzles associated with a single combustion chamber of an engine.